The present invention relates to ophthalmologic devices, and more particularly to an apparatus which aligns a measuring system of an ophthalmologic device with high accurately with a respective one of eyes to be examined such that the measuring system is in a predetermined positional relationship to the eye.
An ophthalmologic device such as a non-contact tonometer or an objective eye refractivity measuring device, and more particularly its measuring system are required to be aligned vertically and horizontally and in distance with a respective one of the eyes to be examined, for measuring purposes, such that the device is put finally in a predetermined positional relationship to the respective one of the eyes.
Conventionally, an alignment mechanism for an ophthalmologic device is known which projects an alignment index image to a respective one of the eyes to be examined, receives a reflected image of a vetex cornea of the eye along with a frontal eye image in an observation unit, and drives a sliding mechanism, for example with a joystick, while viewing a television monitor, such that an optical system of the observation unit is placed in a predetermined positional relationship to the eye. U.S. Pat. No. 5,252,821, U.S. Ser. No. 08/076,745, and U.S. Ser. No. 08/052,916, have been known as prior arts.
The user is required to manipulate the joystick while viewing the TV monitor in the alignment. Thus, when the user is not used to align an ophthalmologic device such as a non-contact tonometer which requires an especially high accuracy of alignment, however, it would take much time for the user to perform the alignment and its accuracy would not be sufficiently high.
In order to handle a device which requires high accuracy of alignment, the user is required to be skilful in the manipulation of the device, and hence to be trained sufficiently to achieve satisfactorily complete manipulation of the device.